Outline

Introduction: Primary affection of the diaphysis of long bones by tuberculosis without articular involvement is very rare. Presenting symptoms are swelling, pain and adynamia. Surgery, curettage of bone marrow and meticulous histopathological examination are indispensable for definite diagnosis and early therapy.

Materials and methods: We report diagnostic steps, therapy management and follow-up of a rare case in a 28-year-old woman of Moroccan origin with primary diaphyseal tuberculosis of the right tibia. A 48-year-old woman (157 cm height, 56,8 kg weight) presented at the outpatient clinic with pain and swelling of the right lower leg for the last 6 weeks.

Results: Since definitive diagnosis of the lesion after conventional diagnostics and first biopsy was not possible a second open biopsy with local exploration and saucerisation of the lesion was performed. The conventional microbiological microscopy (Ziehl-Neelsen) was inconspicuous. The clinical tuberculin test (Mantoux) was performed again and was negative as before as well as a TB IFNg-ASSA assay. Concluding all findings at this point still led to the unspecific diagnosis of a chronic osteomyelitis without a specific origin. Finally only cultured cell samples (8 weeks later!!) of former biopsy material from distal diaphysis finally revealed acid-fast bacilli which then could be characterized to be M. tuberculosis. A scintigraphy showed elevated bone metabolism in the distal tibia. Beside degenerative changes in certain joint structures no further focus could be detected. Radiographic exams of the thorax showed no suspicious lesions there. The final diagnosis was primary isolated diaphyseal tuberculous osteomyelitis of the right tibia.

Conclusion: The patient was offered standard four drug anti-tuberculous regimen comprising rifampicin 600 mg (R), isoniazid 300 mg (I), ethambutol 1,200 mg (E), and pyrafat 1,500mg (P) daily initially for two months (RIPE), followed by a six-month course of isoniazid and rifampicin (IR). In cases with histological biopsy of long bone lesions with unspecific inflammation and sterile microbiology a primary TBC has to be considered.